Embodiments of the present invention relate to a photodiode array, and more particularly, to a method of manufacturing a photodiode array having through-wafer vias.
A photon detector or photodetector (also referred to as a photodiode) is a semiconductor device that converts radiant power (e.g., light) directly into electrical current. Positive-intrinsic-negative (PIN) diodes or PIN photodiodes and negative-intrinsic-positive (NIP) diodes or NIP photodiodes are generally known in the art. A PIN/NIP diode is a form of photodetector. A PIN diode is a type of photodiode with a large, mutually doped intrinsic region sandwiched between p-doped and n-doped semiconductor regions. The PIN diode name comes from the layering of the materials, positive, intrinsic, negative (i.e., PIN). A PIN diode typically exhibits an increase in its electrical conductivity as a function of the intensity, wave length and modulation rate of the incident radiation.
A PIN diode is also a semiconductor device that operates as a variable resistor at radiofrequency (RF) and microwave frequencies. The resistance value of a PIN diode is determined only by the forward bias direct current (DC) current. At high RF frequencies when a PIN diode is at zero or reversed bias, it appears as a parallel plate capacitor, essentially independent of reverse voltage.
Photoconductor or photodiode arrays are groups of a plurality of photodetectors or photodiodes, such as PIN/NIP diodes, that are arranged together on a substrate or a wafer. When many photodiodes are arranged on a substrate, it is desirable to provide back side contacts in order to maximize the surface area of the photo receptive portion of the photodiode on the front surface. Accordingly, it is desirable to provide through-wafer vias to couple an anode/cathode of the photodiode through to the back side of the photodiode array for making contacts. It is further desirable to provide a method of manufacturing a photodiode array with through-wafer vias.